1. Field of the Invention
The present invention relates to an image forming apparatus which is typically represented by electrophotographic copying machines, printers, facsimile machines, etc., and more particularly, to an improvement of control means of an automatic original document feeder which is disposed to such apparatuses.
2. Description of the Related Art
In the case of an electrophotographic copying machine, for example, such a copying machine is in a popular use which comprises an automatic original document feeder which is attached on an original document seater of the copying machine for the purpose of enhancing the copying efficiency of a number of copies of an original document. As a first example of a conventional technique regarding a copying machine with an automatic original document feeder, Japanese Unexamined Patent Publication JP-A 61-111260 (1986) discloses an automatic original document feeder which detects that an original document is set at an insertion part and automatically starts feeding the original document upon the detection and in accordance with an output signal which is supplied after a predetermined period of time under the control of a timer.
In addition, as a second example of the conventional technique, Japanese Unexamined Patent Publication JP-A 4-30179 (1992) discloses an image forming apparatus in which there are at least two or more original document seaters disposed in an automatic original document exchange means and after formation of an image of an original document which is fed from a first original document seater, for instance, is stopped and the absence of the original document on the first original document seater is detected, feeding of another original document is automatically started upon detection of setting of the another original document on the original document seaters.
Further, as a third example of the conventional technique, Japanese Unexamined Patent Publication JP-A 62-169568 (1987) discloses an automatic original document feeder (ADF) which optically detects a mislaid original document before reading an original document when there is the mislaid original document at a stationary original document reading position, stops a subsequent ADF operation, and displays an alarm message which is indicative of the mislaid original document.
By the way, in a copying machine such as the respective examples of the conventional technique which has an automatic start function, an original document sensor turns on and copying is started automatically upon setting of a plurality of original documents to an automatic original feeder. However, where an original document jam occurs as the original documents get jammed, when there still is an original document which is left set in the automatic original feeder after the original document jam is eliminated by removing the jammed original documents, automatic feeding of the original documents is started without waiting for the removed original document to be returned. Hence, an operator must set the unremoved original document to the automatic original feeder once again and copy the jammed original document after copying of all original documents on original document seaters is completed, which in turn changes the order of the original documents.
Further, although copying is suspended as an operator gives a copying suspend instruction for interruption, stopping or the like of copying, in the case that there is an original document which is left set in the automatic original feeder, automatic feeding of original documents is started soon, and the operator cannot suspend the copying despite the instruction.
Still further, when the automatic original feeder is open and an original document is set in the automatic original feeder, as soon as an operator closes the automatic original feeder to perform copying, the original document which is set on the automatic original feeder is automatically fed, thereby creating a situation which is not the operator's intention to perform copying of the other original document. In addition, even when copying of the original document which is set in the automatic original feeder is desired, an impact which is created when the automatic original feeder is closed disturbs the condition in which the original document is set, possibly creating a situation that the original document is fed as it is inclined obliquely at an angle.